Brass, or special metals for aircraft (AMS 4616 or 6414) have, for example, been used for making a retainer for a bearing used for supporting a shaft rotating at a high speed at a high temperature, for example, the shaft of a machine tool, or of a gas turbine for a supercharger, or power generator.
The retainers formed from metallic materials as mentioned have, however, only a limited possibility of reduction in weight. There are known, for example, a retainer formed from a material obtained by impregnating a cotton cloth with a phenolic resin, and a retainer formed from a synthetic resin, such as a thermosetting polyimide resin, as retainers of lighter weight.
The retainers formed by using a phenolic resin have, however, been difficult to manufacture at a low cost on a mass-production basis because of a great deal of labor and time required for their manufacture, as the thermosetting property of the phenolic resin does not permit injection molding, and as a separate job is required for making pockets.
The retainers of a thermosetting polyimide resin have also been expensive to manufacture, since their manufacture also relies upon turning.
It is, therefore, an object of this invention to provide a bearing retainer of a synthetic resin which is suitable for use in a situation involving a high speed of rotation at a high temperature, and which can be manufactured at a low cost.
It is another object of this invention to provide a bearing retainer of a synthetic resin which can be manufactured easily by injection molding without relying upon any separate job for the formation of pockets, and without relying upon any turning job.
It is still another object of this invention to provide a method which can manufacture a bearing retainer of a synthetic resin at a low cost.
It is a further object of this invention to provide a rolling bearing which includes a retainer of a synthetic resin as mentioned above, and is suitable for use in a situation involving a high speed of rotation at a high temperature.
[Essential Features]
The bearing retainer of a synthetic resin according to this invention is formed by injection molding from a material prepared by mixing a thermoplastic resin and particles of a heat-resisting resin.
The bearing retainer according to this invention is preferably formed from a material further including reinforcing fibers.
The thermoplastic resin is preferably selected from among polyether ether ketone (PEEK), polyether ketone (PEK), polyether sulfone (PES), polyether imide (PEI), polyamideimide (PAI), polyphenylene sulfide (PPS), polyallyl ether nitrile (PEN) and a thermoplastic polyimide resin (TPI), and a mixture thereof, while polybenzimidazole (PBI) is used as the heat-resisting resin.
[Advantages]
A retainer of a thermoplastic resin can be made by injection molding, but can withstand use only at a relatively low temperature. A retainer of a heat-resisting resin can withstand use at a relatively high temperature, but as it cannot be made by injection molding, there is no alternative but to rely upon turning for making it despite its higher cost.
The retainer of this invention can be made by injection molding owing to the thermoplastic resin which its material contains, though it also contains the heat-resisting material, while it can withstand use at a high temperature owing to the heat-resisting material.
If its material further contains reinforcing fibers, the retainer is further improved in strength and heat resistance.